Saambou bank deliberately manipulated interest rates on its bond accounts to increase profits at a time when the bank was undergoing a "squeeze on its profit margins".

These are the allegations made by forensic accountant Gregory Johnson, in a report submitted to the North Gauteng High Court in an ongoing case between bond recalculator Emerald van Zyl and FNB, the bank which took over Saambou's home loan book after Saambou was placed under curatorship in 2002.

In 2006, FNB recalculated all the Saambou bonds, and paid back R154 million to clients, but Van Zyl claims this is just the tip of the iceberg.

For the court matter, eight bond accounts were chosen as test cases. In analysing the interest charges on these accounts, Johnson found that:

Six of the eight account holders were originally charged the Saambou base interest rate on their accounts. The other two were charged the base rate, minus 0.75 percent, and the base rate plus 0.25 percent respectively.

Between 1990 and 1999, Saambou started to increase the rates it charged these clients. By 1999, all eight were being charged rates between 0.5 and 3.5 percent higher than the base rate.

Of the eight account holders, only three missed bond payments.

Some of the increases in rates occurred before they missed payments.

The interest rate changes could therefore not have been as a result of a change in the risk profile of the clients.

The analysis of the overcharges runs until 2004, two years after FNB took over the loan book.

Johnson says the reasons for the manipulation had little to do with the risk profile of the clients and more to do with the bank's profitability.

In an affidavit made by Dawid Botha, a former member of the Saambou board of directors, it emerged that to get more people to deposit their money with the bank, Saambou offered higher and more attractive interest rates.

However, this then put a "squeeze" on profit margins, which needed to be managed by increasing the amount of interest paid by home loan clients.

"Increases in the bond debtors' rates above the base rate had nothing to do with how the debtor managed his/her account, or the risk associated with the account. These increases were all related to Saambou's own profitability and Saambou's risk profile, which deteriorated in the late 1990s," Johnson said.

When the bank was placed under curatorship in 2002, about 80 000 home loans were taken over by FNB.

A separate analysis of more than 77 000 Saambou bonds, also done by Johnson, indicates that:

White bond holders paid an average interest rate of 15 percent.

Indian clients paid an average rate of 15.5 percent, and coloured clients an average of 16.5 percent.

Black bondholders were charged an average interest rate of 18 percent.

FNB chief marketing officer Bernice Daniels said: "All matters incidental relating to Saambou will be dealt with thoroughly in the appropriate forum, being the court.

"FNB strongly rejects any allegations that race plays any role in determining the rates applicable to mortgage bonds."

In previous statements, the bank has stated that "the claim of racial discrimination is based on wholly inappropriate and insufficient information for any legitimate conclusion to be drawn".

The bank has also said Van Zyl stands to benefit financially from any amounts recovered if his legal action is successful.

"Since giving interviews to various media, Emerald van Zyl issued a letter to FNB demanding that FNB pay him R1.8m, as well as waive his debt to FNB of R400 000 owed to the bank for legal costs due to the postponement of the trial in November 2011.

"He has threatened to go to the media with further allegations should we not agree to his demands," Daniels said in a previous statement.